Need to configure ramps AUX for a external Y driver

Hi I build a large printer, X:500mm,Y:600, Z:800 with two NEMA 24 motors in Z axis
and two NEMA 23 in Y axis.

I want to have two drivers for the Y axis.
NO want series or parallel conection.

Then need to add a external driver.
The extra driver will be mounted over a
KEYES A4988 Stepper Motor Driver Shield

I read this article to add a third extruder on the AUX-2 RAMPS ports
[reprap.org]

I will use the onboard drive for one Y1 motor
and redirect Y axis steps to AUX-2 ports to external driver for the Y2 motor.

Which are the changes that must to do in marlin firmware?
There is another better alternative?
Greetings

Look in configuration_adv. H there are options for dual motors. I'm not sure an A4988 makes a great driver for a nema 23 motor you're likely to be running the motor at 50% of its max current at most and that's going to be pushing the driver fairly hard. A nema 17 driven at 80% of its max current will probably produce more torque.

If you intended to divert both y1 and y2 step/direction/enable to substantial external drivers that could feed 2.4A+ to your nema 23s you'd be getting what you want out of them.

Edited 1 time(s). Last edit at 06/10/2017 12:24PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

The idea is use the 8825 driver,
but the 4988 not will be a problem,
the NEMA 23 motor current is 1A,
FULLING 57 STH 76 1006 A , 8.6V, 1Amper, 13.5kg/cm
Also the NEMA 24 is 1.4A

The point is how to send Y motor signals to AUX-2


Using MARLIN 1.1.0 RC8 In the configuration_adv.h i define Z dual and Y dual

#define Y_DUAL_STEPPER_DRIVERS

#define Z_DUAL_STEPPER_DRIVERS

When compile have this error

'E2_STEP_PIN' was not declared in this scope

Greetings

when you enable DUAL steppers it steals it from the 'additional' extruders

you need to define E2_STEP_PIN for the pin your using on AUX, in the pins_RAMPS.h file


will also need

#define E2_STEP_PIN
#define E2_DIR_PIN
#define E2_ENABLE_PIN
#define E2_CS_PIN

as a quick test you can set them all to -1 just to see if it complies
But for actual movement you need real pins defined

Thanks,
in the pins_RAMPS.h add the next lines pointing to AUX -2

#define E2_STEP_PIN 64
#define E2_DIR_PIN 59
#define E2_ENABLE_PIN 44
#define E2_CS_PIN 66


And compile good

Just one doubt which is the function of the E2_CS_PIN , where i must to connect it?
Greetings

Edited 1 time(s). Last edit at 06/15/2017 07:37AM by marceloarguello700.

CS pin is only for advanced stepper drivers with SPI interfaces

not needed for A4988

Finally i make the conections.

Changes to do in the Marlin 1.1.0 firmware:

Configuration_Adv.h
Line: 262
#define Y_DUAL_STEPPER_DRIVERS

Line: 271
#define Z_DUAL_STEPPER_DRIVERS

-----------------------------
pins_RAMPS.h
Line: 117
// Add a third extruder named E2 to map Y2 on AUX2
#define E2_ENABLE_PIN 59
#define E2_DIR_PIN 64
#define E2_STEP_PIN 44

The pins order is to match the Keyes conector with the Ramps AUX-2 conector

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